Food and other products are often packaged in containers made from flexible, lightweight, and sturdy materials such as plastic or cardboard. The assignee of the present invention, Luigino's, Inc. of Duluth, Minn., uses a variety of flexible containers for its frozen entrees. One of the later steps on the production line for packaging these entrees is to attach a lid to the container and heat seal the lid in place.
In order to preserve quality, it is essential that each lid's seal is checked. Otherwise, improperly sealed containers will continue through the production line and possibly be shipped to customers. In the past, each container was manually checked by a line operator. Thus, there is a need for an automatic method and apparatus for identifying containers having improperly sealed lids.
It is an object of the present invention to provide a method and apparatus for the automatic identification of improperly sealed lids.
One embodiment of the invention features an air-driven pneumatic cylinder and piston arrangement ("actuator"), including first and second rods attached to the piston. A container is brought under the first rod, and the piston is moved downward. As the first rod impacts the container's lid, the first and second rods "measure" the lid's deflection. If the lid is securely sealed, the lid's deflection is minimal, and thus, the first rod does not travel significantly beyond its point of impact with the lid. If the lid is not securely sealed, the lid deflects and allows the second rod to travel far enough to contact and activate an alarm.
Thus, it is an advantage of this invention that improperly sealed lids are automatically identified in a reliable and efficient manner. It is a further advantage of this invention that human resources are saved by eliminating the need for a manual inspection of each lid's seal.